1. Field of the Invention
This invention relates to an oral composition which allows a cationic bactericide to exert its activity to a full extent, presents no peculiar taste, and is pleasant to use and stable during storage.
2. Prior Art
In the conventional oral compositions, flavors are frequently blended for the purposes of masking peculiar tastes inherent to base ingredients and effective ingredients and improving the feel on use. When a component having a strong peculiar taste, especially, a cationic bactericide having strong bitterness is blended, an oil-soluble flavor is used from the standpoint of titer.
When an oil-soluble flavor is blended in an oral preparation, in turn, an anionic or nonionic surfactant is generally added as a solubilizing agent, which will undesirably deactivate the cationic bactericide. The loss of bactericidal activity can be avoided by blending an excess amount of the cationic bactericide, which will give rise to other problems including harmfullness, storage instability and difficult bitterness masking. In addition, the anionic or nonionic surfactant itself induces mucosa stripping, stimulation and a peculiar taste to the mouth, which will, in turn, cause inconvenience like a change of taste of food and an unpleasant feel on use. For these reasons, a cationic bactericide is conventionally blended in an oral composition at the sacrifice of storage stability, peculiar taste masking, and/or optimum content.
Japanese Patent Application Kokai (JP-A) No. 70443/1979 proposes to use an oil-soluble flavor in essence form in dentifrice compositions for the purposes of masking a peculiar taste and improving the feel on use. This attempt also requires the presence of the above-mentioned surfactant which can lower the activity of a cationic bactericide. JP-A 931/1993 discloses taste improvement by the selected use of a quaternary ammonium salt among cationic bactericides. This method is effective only in the limited range and not applicable to a wide range of use.
Therefore, for oral compositions having cationic bactericides blended therein, there is a need for improvements including high activity of cationic bactericides in a wide range, elimination of a peculiar taste, a pleasant feel on use, and storage stability.